Grain growth kinetics of a fine-grained AZ31 magnesium alloy produced by hot rolling

A study on the kinetics of grain growth of a fine-grained, hot-rolled AZ31 magnesium alloy was carried out by isothermal and isochronal annealing treatments. The grain size of the as-rolled and subsequently annealed sheet samples was determined by metallographic observation using the linear intercept method. It was found that for annealing at temperature in the range of 523-723 K, the effect of annealing temperature, T, and time, t, on the grain growth could be well interpreted by the kinetic equation, Dⁿ - D₀ⁿ = k t, where k = k₀ e^{- Eg / R T}. Based on the experimental data on grain growth obtained by annealing treatments, the grain growth exponent, n, and the activation energy, E_g, were figured out, and these grain growth kinetic parameters were compared with those for other magnesium alloys reported in recent literatures.